Warns if the user fires in unknown commands

src/executables/uber.js

@@ -8,4 +8,10 @@ program.version(pkg.version)
   .description('Figure out if you should order a car to pick you up and drive you to where you want to go')
   .command('price', 'get price estimate')
   .command('time', 'get time to pickup estimate')
+  .arguments('<command>')
+    .action((cmd) => {
+      program.outputHelp();
+      console.log(`\n Unknown command ${cmd}.`));
+      console.log();
+    }) 
   .parse(process.argv);